JPH08200858A - Two-stage compression refrigerator - Google Patents

Abstract

PURPOSE: To automatically smoothly reset to a normal operation without wet vapor suction of refrigerant in a cooler at the time of restarting even if the compressor is stopped due to power interruption or an emergency stop. CONSTITUTION: The opening is regulated at the refrigerant tube 9 of the inlet side of a cooler 12 by a control signal from a controller 15 at the time of normal operation, but when the compressor is stopped due to the power interruption or emergency stop, an expansion valve 11 which is forcibly closed while the operation is stopped is provided. Further, a switching circuit 14 for so controlling to switch a solenoid valve as to continuously feed liquid while always opening the solenoid valve when a predetermined time is elapsed by intermittently feeding liquid by repeatedly switching the solenoid valve for a predetermined time interval when the compressor is restarted after the compressor is stopped at the valve 10 for the expansion valve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stage compression refrigeration system in which the compressor is a two-stage compressor having a low-stage compression section and a high-stage compression section.

[0002]

2. Description of the Related Art A two-stage compression refrigerating apparatus having a two-stage compressor is used for ultra-low temperature refrigeration. Conventionally, when the compressor operation is stopped due to a power outage or an emergency stop, if the compressor is restarted as it is, liquid supply is started with the start of the compressor and the refrigerant is continuously supplied into the cooler. ing.

[0003]

In the ultra-low temperature region, the evaporation pressure of the refrigerant in the cooler is low, and the gas refrigerant in the dry cooler is sucked by the two-stage compressor to reduce the pressure in the cooler. Is less likely to evaporate, and liquid refrigerant that is not vaporized accumulates in the cooler.

Further, when the operation of the compressor is stopped due to a power outage or an emergency stop, the refrigerant in the cooler is not evaporated, so that the temperature of the refrigerant on the outlet side of the cooler rises.
The opening of the expansion valve provided in the refrigerant pipe on the inlet side of the cooler is controlled according to the refrigerant temperature on the outlet side of the cooler. Controlled to be.

When the compressor is restarted in such a state,
Before the temperature and pressure inside the cooler are not sufficiently reduced, more refrigerant than in normal operation will be supplied to the cooler, and the unvaporized refrigerant will accumulate excessively in the cooler, causing liquid backing and normal operation. There was a problem that it could not be smoothly returned to.

Therefore, conventionally, the compressor cannot be automatically restarted, and the compressor is restarted while manually adjusting the opening of the expansion valve to suppress the amount of the refrigerant supplied to the cooler. It was done and was returning to normal operation.

The present invention is a two-stage compression refrigeration system that can automatically and smoothly return to normal operation without the liquid in the refrigerant in the cooler being restarted when the compressor is restarted even if the compressor is stopped due to a power outage or an emergency stop. The purpose is to provide a device.

[0008]

In order to achieve the above object, a two-stage compression refrigerating apparatus according to the present invention comprises a two-stage compressor having a low-stage compression section and a high-stage compression section. The liquid refrigerant discharged from the stage compression section and passing through the condenser is heat-exchanged with the refrigerant in the coil in the container of the intercooler in which a part of the liquid refrigerant is branched and supplied to the cooling coil through the expansion valve. In the two-stage compression refrigeration system that is supplied to the cooler, the opening of the refrigerant pipe on the cooler inlet side is adjusted by the control signal from the controller during normal operation, but the When the operation is stopped, an expansion valve is provided that is forcibly closed while the operation is stopped.The solenoid valve for the expansion valve also restarts the compressor after the operation of the compressor is stopped. Then, the solenoid valve is opened and closed repeatedly at fixed time intervals and intermittently. Is liquid, there as obtained by connecting a close circuit for opening and closing control of the solenoid valve so as to continuously feeding to remain always open the solenoid valve after a certain time.

[0009]

When the operation of the compressor is stopped due to a power outage or an emergency stop, the expansion valve provided in the refrigerant pipe on the inlet side of the cooler is forcibly closed. When the operation of the compressor is restarted, the electromagnetic valve for the expansion valve is opened / closed at regular time intervals by a signal from the opening / closing circuit, and the refrigerant is intermittently fed into the cooler. Further, the amount of liquid to be sent can be suppressed from the time when the expansion valve is closed until the control opening degree is reached.

As a result, the amount of the refrigerant supplied to the cooler is suppressed, so that the non-vaporized refrigerant does not excessively accumulate in the cooler, and the normal operation is smoothly restored.

When a certain period of time has passed after the compressor was restarted, the solenoid valve is always opened, and the refrigerant is continuously fed to the cooler to carry out the normal refrigeration operation.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples of the refrigerating apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. The compressor 1 of the refrigeration apparatus according to the present invention is configured in two stages, a low-stage compression section 1a and a high-stage compression section 1b, and the discharge pipe 2a of the low-stage compression section 1a has a high-stage compression section 1b.
Is connected to the suction side of. Discharge pipe 2 of high-stage compression section 1b
b is connected to the inlet of the condenser 3 through which cooling water is passed through the coil 3a, and is connected to the coil 7a of the intercooler 7 via the solenoid valve 5 and the expansion valve 6 by the outlet refrigerant pipe 4 of the condenser 3. The outlet of the coil 7a is connected to the suction side of the high-stage compression section 1b by the refrigerant return pipe 8.

The outlet of the condenser 3 is also connected to the inlet of the container 7b of the intercooler 7 by the branch refrigerant pipe 4a, and the outlet of the container 7b of the intercooler 7 is expanded electronically with the solenoid valve 10 by the refrigerant pipe 9. Coil 12 of dry cooler 12 via valve 11
The outlet of the coil 12a is connected to the suction side of the low-stage compression section 1a by the refrigerant return pipe 13.

An opening / closing circuit 14 for controlling opening / closing of the solenoid valve is connected to a solenoid valve 10 provided in the refrigerant pipe 9 on the inlet side of the cooling coil 12a of the cooler 12 via a signal line.
The opening / closing circuit 14 is for controlling the opening / closing of the solenoid valve when the compressor is restarted after the compressor is stopped due to a power failure or an emergency stop, and is composed of a timer 14a and a switch circuit 14b. .

It is assumed that the timer 14a of the switching circuit 14 is turned on when the compressor is restarted and turned off after a lapse of a certain time, and the switch circuit 14b is turned on by the timer 1.
While 4a is ON, it turns ON at a fixed time interval,
When the timer 14a is turned off repeatedly, the switch circuit is always turned on.
0 is opened and closed by turning on and off the switch circuit 14b.

A controller 15 for controlling the opening degree of the expansion valve is connected to the expansion valve 11 provided in the refrigerant pipe on the inlet side of the cooling coil 12a of the cooler 12 via a signal line.

The controller 15 is a temperature sensor 1 provided in the refrigerant pipe 13 on the outlet side of the coil 12a of the cooler 12.
6 and the opening of the expansion valve 11 are adjusted based on the temperature and pressure signals from the pressure sensor 17. When the operation of the compressor 1 is stopped due to a power failure or the like, the expansion valve 11 is operated by the compressor. It is forced to remain closed until it is restarted.

The refrigerating apparatus of the present invention constructed as described above operates as follows. The high-temperature refrigerant gas discharged from the low-stage compression section 1a of the compressor 1 is sucked into the high-stage compression section 1b and further pressurized, and then sent to the condenser 3 to be cooled by the cooling water flowing through the cooling coil 3a. It becomes a refrigerant.

The liquid refrigerant from the condenser 3 is decompressed and vaporized by the expansion valve 6 via the electromagnetic valve 5, and the coil 7a of the intercooler 7 is cooled.
To the high-stage compression section 1b.

The liquid refrigerant from the condenser 3 also enters the container 7b of the intercooler 7 from the branch refrigerant pipe 4b and is supercooled by the low temperature gas refrigerant in the cooling coil 7a described above.
After passing through the solenoid valve 10, the pressure is reduced by the expansion valve 11 to be vaporized, sent to the cooling coil 12a of the cooler 12, and taken into the low-stage compression section 1a.

During normal operation, the solenoid valve 10 is opened, and the expansion valve 11 is opened by the controller 15 which issues a control signal based on signals from the temperature sensor 16 and the pressure sensor 17 provided on the outlet side of the cooler 12. The degree is adjusted.

On the other hand, when the operation of the compressor is stopped due to a power outage or an emergency stop, the expansion valve 11 remains closed until the compressor is restarted, and the solenoid valve 10 also remains closed. ing.

When the compressor 1 is restarted, the expansion valve 11 is opened by a signal from the controller 15, and the opening is adjusted according to the temperature and pressure of the refrigerant on the outlet side of the cooler as in the normal operation.

On the other hand, in the opening / closing circuit 14 for controlling the opening / closing of the solenoid valve 10, as shown in FIG. 2, when the compressor is restarted, the timer 14a is turned on and the switch circuit 14b is connected to the timer 1
While 4a is on, it turns on and off at regular intervals.
Repeat F alternately. The solenoid valve 10 is a switch circuit 14b
The liquid is intermittently fed by being repeatedly opened and closed by the ON and OFF signals from.

Due to this intermittent liquid supply, the amount of liquid supplied to the cooler 12 is suppressed, and the excess refrigerant accumulated in the coil 12a is sucked into the low-stage compression section 1a of the compressor 1 during this period and collected. It

After a certain period of time elapses after the compressor is restarted, the timer 14a is turned off, whereby the switch circuit 14b is always turned on and the solenoid valve 10 is opened to continuously feed the liquid. It is designed to return to driving.

The timer 14a is turned off after the compressor is restarted.
As for the length of time until it becomes the temperature, the time taken until the temperature and pressure on the outlet side of the cooler are sufficiently lowered and normal operation is performed is set in advance, and the switch circuit 1
The repeating interval of ON and OFF by 4b is appropriately set according to the refrigerating capacity of the refrigerating device and the like.

In the above embodiment, the temperature sensor 16 and the pressure sensor 17 are connected to the coil 12a of the cooler 12.
The controller 15 controls the opening degree of the expansion valve 11 based on the temperature and pressure signals from these sensors provided on the outlet side, but the controller 15 controls both the inlet side and the outlet side of the coil 12a of the cooler 12. In some cases, the opening degree of the expansion valve 11 is controlled by providing a temperature sensor and comparing the temperatures of the inlet side and the outlet side with a controller.

[0029]

As described above, according to the present invention, when the operation of the compressor is stopped at the inlet side of the cooler due to a power failure or an emergency stop, the electronic components are forcibly kept closed until the operation is restarted. Since it has a built-in expansion valve, the amount of liquid sent can be suppressed from closing to the control opening when the compressor is restarted, and the solenoid valve is an opening / closing circuit that repeatedly opens and closes the solenoid valve at regular time intervals. Since the refrigerant is connected, the refrigerant is intermittently sent to the cooler at the time of restart, and the amount of liquid sent is suppressed.Therefore, excessive refrigerant is supplied to the cooler when the compressor is restarted. Therefore, the refrigeration operation after the compressor is restarted can be smoothly returned to the normal operation.

Therefore, it is possible to save the labor of manually adjusting the opening of the expansion valve at the time of restarting as in the conventional case, and to automatically start up the apparatus.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a two-stage compression refrigeration system according to the present invention.

FIG. 2 is a diagram showing operations of an opening / closing circuit and a solenoid valve.

[Explanation of symbols]

 1 Compressor 1a Low-stage compression part 1b High-stage compression part 2a, 2b Discharge pipe 3 Condenser 3a Coil 4, 4a Refrigerant pipe 5 Solenoid valve 6 Expansion valve 7 Intermediate cooler 7a Coil 7b Container 8, 9 Refrigerant pipe 10 Solenoid valve 11 Expansion Valve 12 Dry Cooler 12a Coil 13 Refrigerant Return Pipe 14 Opening Circuit 14a Timer 14b Switch Circuit 15 Controller 16 Temperature Sensor 17 Pressure Sensor

Claims (1)

[Claims] 1. A compressor comprising a two-stage compressor comprising a low-stage compression section and a high-stage compression section, wherein the liquid refrigerant discharged from the high-stage compression section and passing through the condenser is a part of the liquid refrigerant. In a two-stage compression refrigeration system in which heat is exchanged with the refrigerant in the coil in the vessel of the intercooler that is branched and supplied to the cooling coil through the expansion valve and then supplied to the cooler, the refrigerant pipe on the inlet side of the cooler In addition, the opening is adjusted by the control signal from the controller during normal operation, but when the operation of the compressor is stopped due to a power outage or an emergency stop, the expansion is forcibly closed while the operation is stopped. When the compressor is restarted after the compressor has stopped operating, the solenoid valve for the expansion valve is provided with a valve, and the solenoid valve is repeatedly opened and closed at fixed time intervals to intermittently deliver the liquid. After the lapse of time, the solenoid valve is always kept open to allow continuous liquid transfer. Fame by connecting a close circuit for opening and closing control of the electromagnetic valve two-stage compression refrigeration apparatus.